conveyor belt and plane answered at last ??

[AronSearle]

The wheels cannot go faster than the belt.

They don't have to for the plane to move forward.

The wheels can spin independently of the planes forward movement, again, what do you think brakes on wheels are for?

If you spin the wheels of a plane backwards when it is flying, does it stop, of course not

So why does it matter if the wheels are being spun backwards by a conveyor, the brakes are not on, the engine will pull forwards regardless and the wheels can spin backwards all they like.

 

[doitall]

The wheels cannot go faster than the belt.

They don't have to for the plane to move forward.

So why does it matter if the wheels are being spun backwards by a conveyor, the brakes are not on, the engine will pull forwards regardless and the wheels can spin backwards all they like.

The belt is going one way and the plane is sat on it going the other way.

Who said the wheels are going backwards.

Best you read the original thread and give it some more thought, because it's clearly above your thinking power.

 

[doitall]

the plane is stood on a moving belt and the wheels are turning at the same speed which is what one should expect as the plane is stationary on the starting line.

To move forward it has to go faster than the conveyor.

 

[wobs]

the plane is stood on a moving belt and the wheels are turning at the same speed which is what one should expect as the plane is stationary on the starting line.

To move forward it has to go faster than the conveyor.

Move your throttle:
http://www.airplaneonatreadmill.com/

 

[doitall]

But what is the question really getting at, anyway? There are really two "spirits" of the question. In the first, we're asking "can a plane take off with no runway, if I replace the runway with a treadmill?" The answer, as we know now, is no. The plane must move relative to the ground in order to take off. In another deep-meaning of the question, we're asking "is it possible to prevent a plane from taking off, by moving the runway backwards under it?" The answer again is no, you can't prevent it from taking off.

Quote from wobs link

 

[Trazor]

why do we need friction.

Oh dear you really don't understand physics do you.

Let us assume that the bearings in the wheels are frictionless, then the conveyor belt can impart NO FORCE to the plane, and you could stop the plane moving backwards with one hand.

The small amount of friction imparted in reality, cannot negate the force supplied by the jet engines.

It does not matter what is beneath the plane the power supplied will move the plane forwards, as the rocket engines on the Saturn 5 will move it vertically, same principle.

 

[wobs]

But what is the question really getting at, anyway? There are really two "spirits" of the question. In the first, we're asking "can a plane take off with no runway, if I replace the runway with a treadmill?" The answer, as we know now, is no. The plane must move relative to the ground in order to take off. In another deep-meaning of the question, we're asking "is it possible to prevent a plane from taking off, by moving the runway backwards under it?" The answer again is no, you can't prevent it from taking off.

Quote from wobs link

 

[doitall]

why do we need friction.

Oh dear you really don't understand physics do you.

Let us assume that the bearings in the wheels are frictionless, then the conveyor belt can impart NO FORCE to the plane, and you could stop the plane moving backwards with one hand.

The small amount of friction imparted in reality, cannot negate the force supplied by the jet engines.

It does not matter what is beneath the plane the power supplied will move the plane forwards, as the rocket engines on the Saturn 5 will move it vertically, same principle.

Thanks for the laugh.

 

[AronSearle]

doitall.

You have descended into smilies and insults, please, do carry on you silly sausage.

But I am still unsure what force you think is being applied that stops the engines moving the plane forward, almost frictionless wheels?

God forbid if the pilot puts the wheel breaks on in mid flight in your reality!

 

[doitall]

doitall.

You have descended into smilies and insults, please, do carry on you silly sausage.

No insults in any of my posts unless it's a quote from another poster.

 

[crank39]

The engine will pull forwards regardless and the wheels can spin backwards all they like.

No ones disputing that the plane can't move forward while the conveyor is moving backwards, it can but it just means the engine needs to throttle up and it'll move forward, after all its pulling at the air in front of the prop not driving the wheels.

But this is the thing Aron, the original question stated that the conveyor speed matched the plane speed (i'm assuming they knew the knots for a given engine rpm) and set the conveyor at the same speed but backwards, in which case the plane would not pull forward until it throttled up...........just like your analogy of someone on a treadmill pulling themselves forward, yes they would overcome the motion of the treadmill but thats not 'all things being equal' is it

What the question was meant to ask i think was imagine a model plane (for now), sit it on a long dining table on top of a table cloth, pull the cloth out from under the plane and.........WHAT WOULD HAPPEN, would it take off or wouldn't it

My take on it is NO, the wheels would spin of course but with no air flow over the wings it could never take off, now start the engine and throttle up as the cloth is pulled then yes you will move forward...........but thats NOT what the original myth was

 

[joe-90]

For crying out loud. READ NEWTON'S THIRD LAW.

The wheels, conveyor or the colour of the stewardess's knickers don't come into it.

Why does a rocket push forward in space?

NEWTON'S THIRD LAW.

 

[UriBentMySpoon]

If the planes forward speed is matched exactly by the conveyor belt going the other way then the plane will not move relative to the Earth. If you run too fast on your running machine you move forward, too slow you move backwards.

 

[joe-90]

If the planes forward speed is matched exactly by the conveyor belt going the other way then the plane will not move relative to the Earth. If you run too fast on your running machine you move forward, too slow you move backwards.

Now imagine you are on that treadmill on a unicycle and have a rocket pack on your back. Now what happens? NEWTON'S THRID LAW.

 

[joe-90]

Where's that spell checker.